Protective device



Patented Sept. 8, 1942 PROTECTIVE DEVICE George F. Lincks, Pittsfleld, Mass, assignor to General Electric Company, a corporation of New York Application June 25, 1940, Serial No 342,259

19 Claims. (Cl. 200118) My invention relates to a protective device and to a, mechanism having an electric discharge device for controlling the movement of a part which is operatively connected to a suitable portion of the protective device such as a switch mechanism or indicator, and although not, limited thereto, it has particular application to an operating device for a ulrcuit breaker mechanism such as may be found in loop sectionalizing cutouts.

Sectionalizing cutouts, and particularly those used in street lighting series circuits, have been provided with a gap or a film cutout, in series with a fuse member for disconnecting a faulty loop from the series circuit. Also gap by-passes, as evidenced by Patent 1,971,194 to McEachron et al., have been applied in cutout applications with arrangements for short circuiting the gaps so as to provide ashort circuiting path across the terminals of the faulty loop at the point where these terminals are connected with the feeder line. The gap by-pass is desirable, since with it, a protective device can be employed which will differentiate between a high voltage surge of short duration, such as that caused by lightning, and a sustained power overvoltage, such as caused by an open circuit in the loop to which the device is connected.

However, I have found it desirable to employ an electric discharge device which may not only incorporate the desirable discriminative characteristics which are present in a gap by-pass, but which will also operate a circuit breaker arrangement in an improved and efficient manner for isolating the defective loop and to provide a path around that loop so that the remaining loops will continue to receive power.

It is, therefore, an object of my invention to provide. a protective device with an improved electric discharge device. v

Another object of my invention is to provide a protective device with an improved mechanism for releasably holding a movable member or part of the device in a predetermined position.

Another object of my invention is to provide an improved protect ve device with such characteristics that it will distinguish between a high voltage surge of short duration and of sustained power overvoltage.

A further object of'my invention is to provide a circuit breaker mechanism for a loop sectional zing cutout which will electrically disconnect a faulty loop and at the same time short circuit the feeder line across the loop contacts in an improved and eflicient manner.

I accomplish these, as well as other objects, by providing a mechanism or operating device which includes an improved electric discharge device having relatively movable electrodes and which may discriminate between a sustained power overvoltage and a surge of short duration for controlling the movement of a part which is movable from one position to another for the accomplishment of a predetermined function, such as the operation of a switch mechanism or indicator. This operating device has particular application in protective devices, such as loop sectionalizlng cutouts, which maybe connected between a power feeder and each of a plurality of serially connected loops, as may be found in street lighting. In such power apparatus it is important to provide an arrangement which will disconnect one faulty loop but which will allow the remaining loops which are ordinarily connected in series with the faulty loop to remain in operation. This is accomplished by means of a cutout which will by-pass the circuit across the faulty loop. The operating arrangement for such a cutout is of the utmost importance, and I provide an improved arrangement which includes a gap and an operative connection such as a latch for operating the movable part or releasably holding the movable part in a predetermined position. A heat responsive means is mounted adjacent the gap so that upon a sustained power overvoltage, which comes as a result of an open circuit in the loop, the heat responsive means will function upon becoming overheated or will respond to a predetermined arcing across the gap and allow the latch to move to an unlatching position. This will cause the movable part to be released in order to allow the cutout to operate so as to disconnect the faulty loop and at the same time short circuit the feeder line across the faulty loop so that the other loops will remain in operation.

Further objects and advantages of my invention will become apparent from the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing Fig. 1 is a sectional side elevation of a drop-out loop sectionalizing cutout provided with an embodiment of my invention; Fig. 2 is a front view of the housing of the cutout illustrated in Fig. 1, the cover having been removed; Fig. 3 is a front view of the inside. of

the cover of the cutout illustrated in Fig. 1; Fig.

4 is a sectional side elevation of the cutout box and the cover illustrated in Fig. 1, the cover having moved to a drop-out position; Fig. 5 is a skeleton view of the conducting members of the cutout illustrated in Fig. 1; Fig. 6 is a sectional side elevation of my improved electric discharge device which is employed as a part of the operating mechanism of. the cutout illustrated in Fig. 1; Fig. 7 is an end view of the device illustrated in Fig, 6; and Fig. 8 is a diagrammatic view of a plurality of serially connected loops such as may be found in street lighting circuits with my improved sectionalizing cutout being connected between each loop and the feeder circuit.

Referring to the drawing, in Fig. l I have illustrated a drop-out loop sectionalizing cutout which is provided with my improved holding mechanism or operating arrangement. However, it is to be understood that my invention may have application in any other circuit breaker arrangement or in any device where the movement of a movable part as a result of an overvoltage is desired. The cutout illustrated in Fig. 1 includes a housing i and a suitable movable part such as a door H, which is hinged at |2 to one end of the housing i0 so that the door may move from a closed position as shown in Fig. l to an open position as shown in Fig. 4. The movement of this part or door from the one to the other position may accomplish any suitable function, such as a. switching operation or an indicating operation, or both. The switching operation effected by the movement of the door will be described below, and it will be seen that the movement of the door also gives a visual indication that this switching operation has taken place. The housing also carries my improved operating device or mechanism which includes the electric discharge device l3 and which may releasably hold any suitable part, such as the door I I, in any suitable position, and it will be more completely hereinafter described. In order that the cutout may be connected to a source of power through feeder lines, such as indicated by the numerals i4 and i in Fig. 8, I provide terminals i5 and i1 near the top of the housing member l0. Thus the terminal It may be connected to the line H and the terminal ll to the line i5. In order that the cutout may also be connected to lines I 8 and IQ of the loop circuit, I provide at the bottom of the housing l0 terminals and 2| which may be connected to the lines i8 and i9 respectively. It will be seen therefore that the sectionalizing cutout is connected between the lines I 4 and 5 and i8 and Hi.

If some fault such as an open circuit therefore occurs in the loop fed by the lines i8 and I! it is desirable, especially in the case of the hazard of a line falling to the ground, to be able to electrically disconnect the lines I 8 and 9, and at the same time short circuit the lines i4 and I5, that is, toconnect the lines l4 and I5 together so that the remaining series loops will not permanently remain out of circuit.

In order that the cutout may sectionalize a faulty loop and keep the remaining loops connected to the source of power I provide a circuit breaker arrangement in the cutout which includes contacts 22 and 23 which are placed at the top of the housing and may be clearly seen in Figs. 2 and 5. The contact 22 is electrically connected to the terminal i6 through a bolt member 24, while the contact 23 is electrically connected to the terminal I! through a bolt member 25. On the door H I provide cooperating contacts 26 and 2? so that when the door is in its closed position as illustrated in Fig. 1, contact 22 makes electrical connection with contact 28, while contact 23 makes electrical connection with contact 21. The power from the lines l4 and I5 is therefore brought to the contacts 26 and 21, and in order to electrically connect these latter contacts to the terminals 20 and 2| so that the loop l8, l8 may be electrically connected to the lines l4 and II, I provide bus bars 28 and 23 on the door II which may be seen more clearly in Fig. 3. When the door is in its closed position the bus bar 28 which is permanently connected to the contact 28 through a rivet 30, will be electrically connected to the terminal 20 through a bus bar II which is also carried by the housing. This bus bar 3| is electrically connected to the terminal 28 through a bolt member 32 and it also makes contact with the bus bar 28 through a curved end portion 83 at the adjacent end of the bus bar 28. In order to operatively connect my holding mechanism to the movable door the bus bar 28 has an inwardly extending portion 34 with a latch member 3' which, when the door is in its closed position, is held behind a cooperating latch member 36 which is in turn held by or is integral with a bus bar 31. The bus bar 31 is electrically connected to the terminal 2| and is held in latching position by my discharge device I3. It will therefore be seen that when the cover member II is in its closed position the feeder lines l4 and i5 will be electrically connected to the loop lines I8 and |9 through the electrical circuits described above. These circuits may be clearly seen in the skeleton view of Fig. 5. Tracing the circuit therefore from the feeder line l4, through the loop, to the line i5 it will be seen that the circuit includes contact bolt 25, contact 23, contact 21, bus bar 29, bus bar 34, latch members 35 and 36, bus bar 31, to the loop contact 2|. The circuit then includes the loop back to the contact 28 which is electrically connected to the bus bar 3| through bolt 32. The circuit therefore returns to the line l5 through bus bar 28, contacts 26 and 22, connector bolt 24 and terminal I6.

In order to provide an arrangement which will cause the door to drop open when some fault occurs, such as one causing a sustained overvoltage, I provide my improved electric discharge device l3 for operating a latch or latching arrangement which includes the latch members 38 and 36 which are shown in latching position in Fig. 1. This electric discharge device is of such a type that it will discriminate between a sustained power overvoltage and a relatively high voltage of short duration. Such discriminative characteristics are desirable so that the cutout door will not drop out when lighting strikes the circuit, since a lighting stroke is not a fault which should cause a loop to be disconnected. In order that the voltage appearing in the lines may be impressed across my device, it has terminals 38 and 39 which are electrically connected to bus bars 3| and 31 respectively. As will be seen in Fig. 6, my electric discharge device includes electrodes 48 and 4| which are disposed to define a gap 42 therebetween. The terminal 38 is the head of a rivet which forms the electrode 40, and the terminal 39 is the outside end of a sleeve member-43, which is fastened to the electrode 4| in any suitable manner as by welding or the like and whose function will be more completely hereinafter described. Thus, the .voltage appearing across the terminals l6, l1 and 20, 2| will be impressed across the gap 42. The electrode 4|! is solidly mounted on the plate member 44 and the electrode 4| is movably mounted since the sleeve member ll is siidably mounted on the plate member 40. The plate members 44 and ll are in turn held in proper spaced relatlon'to each other by a cylindrical member 40. The end of the sleeve member 43 which extends through the plate member ll has three prongs a which extend through cooperating slots a in the piatemember I. Instead of mounting one of the electrodes for movement, the discharge device may be arranged so that both electrodes are relatively stationary and a cooperating movable member such as the slide 43 releasably held by the heat responsive means.

As will be seen in Fig. 1, the slide or sleeve member ll is operatively connected to the bus bar 31 so as to control its movement. The bus bar 31 is designed to causethe latch member I. to tend normally to move away from the latch member I! or to an unlatching position. This may be obtained in any suitable manner, such as through the inherent resiliency in the bus bar II. This 'movement,however, is restrained by a suitable connection between the sleeve member."-

and a relatively stationary part of the electrical discharge device, the connection being arranged pears across the gap as a result of some fault in the loop, the gap will arc over and the arcing will persist, causing the meltable material to melt. This will remove the restraining force from the latch and the biasing means, which is the natural resiliency of the bus bar 31, willcause the latch member 36 to move away from its cooperating member I! so that the latch mechanism can move to an unlatching position, as shown in Fig. 4. Before the door drops open however the electrodes will be short circuited by the movement of the slide 43 and electrode 4i so that arcing will be stopped by the short circuiting of the electrodes. This is desirable, though not necessary, since the cutout box will be protected from the continued arcing which to function or remove its restraining force upon overheating. Thus the electrode II is connected 2 to the plate member 45 through a rivet member 41, the connection including-a heat responsive arrangement or meltable member 8. This meltable member 48 may extend through a hole 40 in the electrode 4i and around the space between the end of the rivet member 41 and the adjacent surface of the electrode 4 l. Thus a sweated joint is formed between the electrode ll and the rivet 41. Instead of employing a meltable member which will melt upon the application of heat due to arcing across the electrodes any other arrangement which may be designed to perform the same function as the meltable member it may be employed.

This electric discharge device which includes the electrodes, the meltable member, and the cylindrical supporting member may be made to have the desirable discriminative characteristics by following the teachings of Patent 1,971,194- McEachron et al., or co-pending patent application Serial No. 342,282-A11en, both of which are assigned to the same assignee as this present invention. In the by-pass disclosed in the Mc- Eachron patent, the discriminative characteristics are obtained by the use of a non-linear resistance material as the support member 48, while in the Allen application these characteristics are obtained by providing a gap of such width that when it is connected across a line whose minimum normal voltage is at least a certain minimum value. it will have, according to the Allen invention. these desirable characteristics.

The operation of the cutout is as follows: when some high voltage surge of short duration, such as a lightning stroke, strikes either the feeder lines or the loop, the steep wave will travel to the electrodes 40 and ll and cause them to are over. When the power following current, however, approaches zero the arc will stop and the gap, having such characteristics that it will deionise at a faster rate than the rate of recovery voltage, will therefore reseal, and sumcient heat will not be developed to melt the melt-able material I. By resealI mean that the arc will be extinguished before it causes the member to be suflciently overheated to function. However, when a voltage of suilicient magnitude apwould otherwise until the door dropped open. At the same time, however, the door Ii will begin to swing outwardly on its pivot l2 due to the force of a spring member 50. This spring member carries a short-circuiting bar 5| which when the door is closed, is held away from the contacts 22 and II by a boss member 52 which is on the inside of the door ll. However, when t fo due to memes being in its latching Y position, is removed .the spring. II will push against the bar II which in turn pushes against the boss member 52-. Since there is no force to offset the-force of this spring ill, because the latch has moved to an unlatching position, the a cover Ii willswing on its pivot l2 until it takes up the position as shown-in Fig.4, or until it drops further to a vertical position. At the same time the short-circuiting bar 5| will contact a downwardly extending portion 22a of the contact 22 and a similar portion 23a. of the contact 23.

Since the contacts 22 and 23 are connected directly to the terminals l6 and I1 respectively, these latter terminals will be short circuited by the bar ll. Thus the current will be by-passed through the short circuiting member 5| so that the remaining serially connected loops will be kept connected to the source of potential, and the faulty loop will be disconnected by the dropping open of the door Ii so that the damaged loop will be unable toinjure a person who comes in contact with it.

In view of the foregoing it will be seen that I have provided a protective device with an improved mechanism for releasably holding a movable part in one position, which is particularly suitable to be employed as an operating device for a loop sectionalizing cutout, such as are employed in street lighting. In addition, this mechthe dropping-out of the cover of the cutout and at the same time short circuit the terminals in the cutout which are connected to the feeder line. These desirable results are accomplished through an operating device which includes an electric discharge device which has the desirable discriminative characteristics such that it will operate the cutout when a fault occurs, but which will not operate the cutout when a mere high voltage surge of short duration strikes either the loop or the feeder. Thus by employing an electric discharge device which, instead of merely short circuiting its electrodes so as to act as a by-pass, provides for positive movement of a movable part through an improved arrangement responsive to a predetermined arcing,

I am able to disconnect the faulty loop as well as to short circuit the terminals around the loop so that there will be no danger to any person who should happen to come in contact with the faulty line.

Modifications of the particular arrangements which I have disclosed embodying my invention will occur to those skilled in the art, so that I do not desire my invention to be limited to the particular arrangements set forth and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A protective device including a latching means biased to an unlatching position and an electric discharge device for operating said latching means having electrodes disposed to define a gap and heat responsive means adjacent said gap and operatively connected with said latching means for restraining said latching means in its latching position, said heat responsive means being adapted to function upon overheating so as to remove its restraining effect, said gap having such characteristics that upon connection across a source of potential it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said heat responsive means to overheat due to the proximity of said are and function upon a sustained overvoltage so that said restraining means is removed whereby said latching means may move under the influence of its biasing means to an unlatching position.

2. A protective device including a latching means biased to an unlatching position, an electric discharge device for operating said latching means having electrodes disposed to define a gap and heat responsive means adjacent said gap and operatively connected with said latching means for restraining said latching means in its latching position. said heat responsive means, being adapted to function upon overheating so as to remove its restraining effect, and means for connecting said gap across a source of potential, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said heat responsive means to overheat due to the proximity of said are and functic-n upon a sustained overvoltage so that said restraining means is removed whereby said latching means may move under the influence of its biasing means to an unlatching position, said latching means upon movement to its unlatching position causing said source to be disconnected from said gap.

3. A protective device including a latching means biased to an unlatching position, an electric discharge device for operating said latching means having electrodes disposed to define a gap and heat responsive means adjacent said gap and operatively connected with said latching means for restraining said latching means in its latching position, said heat responsive means being adapted to function upon overheating so as to remove its restraining effect, means for connecting said device between a source of potential and a load circuit, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said heat responsive means to overheat due to the proximity of said are and function upon a sustained overvoltage so that said restraining means will be removed whereby said latching means may move under the influence of its biasing means to an unlatching position, and means operable upon said unlatching movement of said latching means for disconnecting said load and device from said source.

4. A protective device having connection between a source of potential and a load circuit including an electric discharge device having electrodes disposed to define a gap and a member adjacent said gap, said member being adapted to function upon overheating, a latch, means for biasing said latch to an unlatching position, means including said member for restraining said latch in its latching position, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said member to overheat due to the proximity of said are and function upon a sustained overvoltage so that said restraining means is removed whereby said latch may move under the influence of its biasing means to an unlatching position, and means operable upon said unlatching movement of said latch for disconnecting said load circuit and said electric discharge device from said source.

5. A circuit breaker mechanism including an operating device having electrodes disposed to define a gap and a member adjacent said gap, said member being adapted to function upon overheating, a latch, means for biasing said latch to an unlatching position, and means including said member for restraining said latch in its latching position, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said member to overheat due to the proximity of said are and function upon a sustained overvoltage so that said restraining means is removed whereby said latch may move under the influence of its biasing means to an unlatching position, said circuit breaker being operable upon said unlatching movement of said latch.

6. A circuit breaker mechanism including a latch, a slide member, electrodes disposed to define a gap, a member adjacent said gap, said member being adapted to function upon overheating, said slide electrodes and member forming an operating device for said breaker, and means for biasing said latch to an unlatching position, said slide member and said meltable member providing a means for restraining said latch means in its latching position, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said member to overheat and function upon a sustained overvoltage so that said restraining means is removed whereby said latch may move under the influence of its biasing means to an unlatching position, said circuit breaker being operable upon said unlatching movement of said latch means.

7. A cutout havin electrical connection between a source of power and a load circuit including an operating device having electrodes disposed to define a gap and a meltable member adjacent said gap, a latch, means for biasing said latch to an unlatching position, means including said meltable member for restraining said latch in its latching position, said gap havin such characteristics that it will are over upon a rd latching position,

switch mechanism for connecting saidelectrodes 20 tively high voltage surge of short duration and then reseal and will are over and cause said member to melt due to the proximity of said are upon a sustained overvoltage so that said restraining means is removed whereby said latch may move latch to an unlatching position, a slide member operatively connected to said latch means, said slide member and said meltable member providing a means for restraining said latch in its and means including said to a source of potential having a normal voltage value, said electrodes upon a sustained overvoltage being impressed across it allowing arcing to appear across said gap causing said member to melt so that said slide may move away from said latch means whereby said latch may move under the influence of its biasing means to an unlatching position, said circuit breaker means being operable upon said unlatching movement of said latch.

9. A cutout having electrical connection between a power feeder circuit and a load circuit including circuit breaker means for disconnecting said load circuit from said feeder circuit and for short circuiting said feeder circuit across said load circuit, an operating device having electrodes disposed to define a gap and a meltable member adjacent said gap, a latch, means for biasing said latch to an unlatching position, and means including said meltable member for restraining said latch in its latching position, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said member to melt due to the proximity oi said arc upon a sustained overvoltageso that said restraining means is removed whereby said latch may move under the influence of its biasing means to an unlatching position, said circuit breaker being operable upon said unlatching movement of said latch.

10. A seetionalizing cutout having connection between a loop circuit and a feeder circuit including a housing, a hinged door, a circuit breaker means operable upon opening of said door to disconnect said loop from said feeder and for short circuiting said feeder circuit across said loop circuit, an operating device having electrodes disposed to define a gap and a meltable member adjacent said gap, a latch, means for biasing said latch to an unlatching position, and means ineluding said meltable member for restraining said latch in its latching position, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will arc over and cause said 55 member to melt due to the proximity of said arc upon a sustained overvoltage so that said restraining means is removed, whereby said latch may move under the influence of its biasing means to an unlatching position, said door being movable to its open position upon the last mentioned movement of said latch.

11. A loop sectionalizing cutout having connection between a loop circuit and a feeder cirnals mounted in said housing, said terminals having electrical connection with said 1009 circuit, a circuit breaker means operable upon opening of said door to disconnect said loop from said feeder and for short circuiting said feeder circuit across said loop circuit. an operating device having electrodes disposed to define a gap and a meltable member adjacent said gap, said device being mounted in said housing, said electrodes being connected across said loop through said terminals, a latch, means for biasing said latch to an unlatching position, and means including said meltable member for restraining said latch in its latching position, said gap having such characteristics that it will are over upon a relatively high voltage surge of short duration and then reseal and will arc over and cause said member to melt due to the proximity of said are upon a sustained overvoltage so that said restraining means is removed whereby said latch may move under the influence of its biasing means to an unlatching position, said door being movable to its open position upon the last mentioned movement of said latch.

12. In an electric protective device, a part movable from one position to another for accomplishment of a predetermined function, and mechanism for releasably holding said part in said one position, said mechanism including an electric discharge device having electrodes disposed to define a gap and heat responsive means adjacent said gap, said mechanism being operatively connected with said part so as to release said part upon said heat responsive means being overheated, said gap having such characteristics that upon connection across a source of potential it will arc over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said heat responsive means to overheat due to the proximity of said are upon a sustained overvoltage so that said mechanism may release said part.

13. In an electric protective device, an indicating part movable froma non-indicating to an indicating position, and mechanism for releasably holding said part in said non-indicating position, said mechanism including an electric discharge device having electrodes disposed to define a gap and heat responsive means adjacent said mechanism being operatively connected with said part so as to release said part so that it may move to said indicating position upon said heat responsive means being overheated, said gap having such characteristics that upon connection across a source of potential it will are over upon a relatively high voltage surge of short duration and then reseal and will arc over and cause said heat responsive means to over-heat due to the proximity of said are upon a sustained overvoltage so said part may move to said indicating position.

. 14. In an electric protective device, a part movable irom one to another position to accomplish a switching operation, and mechanism for releasably holding said part in said one position, said holding mechanism including an electric discharge device having electrodes disposed to define a gap and heat responsive means adjacent said gap, said holding mechanism being operatively connected with said part so as to release said part so that it may move to said other position upon said heat responsive means being overheated. said gap having such characteristics that upon connection across a source of potential it cult including a housing, a hinged door, termiwill arc over upon a relatively high voltage surge of short duration and then reseal and will are over and cause said heat responsive means to overheat due to the proximity of said arc upon a sustained overvoltage so that said part may move to said other position to accomplish said switching operation.

15. In an electric protective device, a part movable from one position to another position for accomplishment of a predetermined function, a mechanism operatively connected with said part for releasably holding said part in said one position, said mechanism including an electric discharge device having relatively movable electrodes normally disposed to define a gap and heat responsive means for releasably restraining said electrodes against relative movement, said heat responsive means being operative to release said electrodes for relative movement in response to predetermined arcing across said gap so that said mechanism may release said part.

16. In an electric protective device, an indicating part movable from a non-indicating to an indicating position, and mechanism for releasably holding said part in said non-indicating position, said mechanism including an electric discharge device having relatively movable electrodes normally disposed to define a gap and heat responsive means for releasably restraining said electrodes against relative movement, said heat responsive means being operated to release said electrodes for relative movement in response to predetermined arcing across said gap so that said part may move to said indicating position.

17. In an electric protective device, a part movable from one to another position to accomplish a switching operation, and mechanism for releasably holding said part in said one position, said mechanism including an electric discharge device having relatively movable electrodes normally disposed to define a gap and heat responsive means for releasably restraining said e ectrodes against relative movement, said heat responsive means being operative to release said electrodes for relative movement in response to predetermined arcing across said gap so that said part may move to the said other position to accomplish said switching operation.

18. An operating device for a cutout including an electric discharge device having relatively movable electrodes normally disposed to define a gap, heat responsive means for releasably restraining said electrodes against relative movement, said heat responsive means being operative to release said electrodes for relative movement in response to predetermined arcing across said gap, and means movable upon relative movement of said electrodes to actuate the cutout.

19. In an electric protective device, a part movable from one position to another position for the accomplishment of a predetermined function, mechanism for releasably holding said part in one of said positions said mechanism including an electric discharge device having electrodes disposed to define a gap, extending from said mechanism, and heat responsive means adjacent to said gap for releasably restraining said means extending from said mechanism, said heat responsive means being operative to release said means extending from said mechanism in response to the heat produced by a predetermined arcing across said gap so that said mechanism may release said part in order that said part may move tosaid other of said positions.

GEORGE F. LINCKS.

movably mounted means 

